Deep-level transient spectroscopy of AlGaAs and CuInSe2

Abstract

Abstract A new technique is used to obtain the activation energies and capture cross-sections of closely spaced traps. It is applied to single-crystal p-type CuInSe2 prepared by the vertical Bridgeman method and selenium-doped Al x Ga 1−x As (x = 0.27) grown by metal-organic chemical vapor deposition. Deep centers, which are active in the same temperature range, usually yield overlapping peaks in conventional deep-level transient spectroscopy rate-window spectra. The digitally recorded capacitive transients are analyzed directly by fitting a double exponential to the data. This fitting produces two Arrhenius plots which yield the trap depths of the two defects. This technique revealed two hole traps for CuInSe2 at 423 and 489 meV. Likewise, for AlGaAs, electron traps were discovered at 435, 455 and 368 meV. The first two energy levels were obtained by applying the double exponential fit in the temperature range 214–246 K. The energy level of the third state was the result of a single exponential fitting in the temperature range from 184 to 214 K after subtracting the two known traps from the transient. It will also be shown that the agreement between the new technique and the standard technique is excellent, and considerably more information about the traps is obtained.